Abiotic is the right answer
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Answer:
Hydrogen bonding is a special type of dipole-dipole interaction that occurs between the lone pair of a highly electronegative atom (typically N, O, or F) and the hydrogen atom in a N–H, O–H, or F–H bond.
Answer:
B) ) –1615.1 kJ mol^–1
Explanation:
since
SiO2(s) + 4 HF(aq) → SiF4(g) + 2 H2O(l) ∆Hºrxn = 4.6 kJ mol–1
the enhalpy of reaction will be
∆Hºrxn = ∑νp*∆Hºfp - ∑νr*∆Hºfr
where ∆Hºrxn= enthalpy of reaction , ∆Hºfp= standard enthalpy of formation of products , ∆Hºfr = standard enthalpy of formation of reactants , νp=stoichiometric coffficient of products, νr=stoichiometric coffficient of reactants
therefore
∆Hºrxn = ∑νp*∆Hºfp - ∑νr*∆Hºfr
4.6 kJ/mol = [1*∆HºfX + 2*(–285.8 kJ/mol)] - [1*(–910.9kJ/mol) + 4*(–320.1 kJ/mol)]
4.6 kJ/mol =∆HºfX -571.6 kJ/mol + 2191.3 kJ/mol
∆HºfX = 4.6 kJ/mol + 571.6 kJ/mol - 2191.3 kJ/mol = -1615.1 kJ/mol
therefore ∆HºfX (unknown standard enthalpy of formation = standard enthalpy of formation of SiF4(g) ) = -1615.1 kJ/mol
Answer:
10.86
Explanation:
Given that:
Concentration = 0.0288 M
Consider the ICE take for the dissociation of ammonia as:
NH₃ + H₂O ⇄ NH₄⁺ + OH⁻
At t=0 0.0288 - -
At t =equilibrium (0.0288-x) x x
The expression for dissociation constant of ammonia is:
![K_{b}=\frac {\left [ NH_4^{+} \right ]\left [ {OH}^- \right ]}{[NH_3]}](https://tex.z-dn.net/?f=K_%7Bb%7D%3D%5Cfrac%20%7B%5Cleft%20%5B%20NH_4%5E%7B%2B%7D%20%5Cright%20%5D%5Cleft%20%5B%20%7BOH%7D%5E-%20%5Cright%20%5D%7D%7B%5BNH_3%5D%7D)
x is very small, so (0.0288 - x) ≅ 0.0288
Solving for x, we get:
x = 7.2×10⁻⁴ M
pOH = -log[OH⁻] = -log(7.2×10⁻⁴) = 3.14
Also,
pH + pOH = 14
So, pH = 10.86
